I also had the problem of suddenly no sound - after my stomp worked fine since years. And it was on day 3 of a 22 day long tour... So I was quite pissed. The other solutions (turning off and on again etc.) did not work.
BUT: This tour was the first time I used an expression pedal (OBNE expression ramper) controlling the output of the Shuffling Looper. So I unplugged the expression input and: Tadah! Everything worked fine since 17 shows now!
So it maybe worth a try for others with the same problem
